U.S. patent application number 13/977283 was filed with the patent office on 2013-12-12 for system and device for neonatal resuscitation and initial respiratory support.
This patent application is currently assigned to VENTINVENT AB. The applicant listed for this patent is Thomas Drevhammar, Kjell Nilsson. Invention is credited to Thomas Drevhammar, Kjell Nilsson.
Application Number | 20130327332 13/977283 |
Document ID | / |
Family ID | 46638835 |
Filed Date | 2013-12-12 |
United States Patent
Application |
20130327332 |
Kind Code |
A1 |
Nilsson; Kjell ; et
al. |
December 12, 2013 |
SYSTEM AND DEVICE FOR NEONATAL RESUSCITATION AND INITIAL
RESPIRATORY SUPPORT
Abstract
The present invention relates to a device and a system for
positive pressure ventilation and continuous positive airway
pressure (CPAP) treatment for neonatal resuscitation and initial
respiratory support. The device and system are designed and tested
for preterm and term neonatal use. The device is easy to use and
allows rapid switch between PPV and CPAP without change of
equipment and significantly reduces the imposed work of breathing
for a breathing child treated with CPAP.
Inventors: |
Nilsson; Kjell; (Ostersund,
SE) ; Drevhammar; Thomas; (Ostersund, SE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Nilsson; Kjell
Drevhammar; Thomas |
Ostersund
Ostersund |
|
SE
SE |
|
|
Assignee: |
VENTINVENT AB
Ostersund
SE
|
Family ID: |
46638835 |
Appl. No.: |
13/977283 |
Filed: |
February 8, 2012 |
PCT Filed: |
February 8, 2012 |
PCT NO: |
PCT/SE12/50119 |
371 Date: |
August 26, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61440409 |
Feb 8, 2011 |
|
|
|
Current U.S.
Class: |
128/205.24 |
Current CPC
Class: |
A61M 2202/0208 20130101;
A61M 2016/0027 20130101; A61M 16/1015 20140204; A61M 2016/003
20130101; A61M 2202/0208 20130101; A61M 2240/00 20130101; A61M
2202/0007 20130101; A61M 16/209 20140204; A61M 16/12 20130101; A61M
16/0816 20130101; A61M 16/0057 20130101 |
Class at
Publication: |
128/205.24 |
International
Class: |
A61M 16/00 20060101
A61M016/00; A61M 16/20 20060101 A61M016/20; A61M 16/08 20060101
A61M016/08 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 8, 2011 |
SE |
1150092-3 |
Claims
1. A device for positive pressure ventilation and continuous
positive airway pressure treatment for neonatal resuscitation
comprising: a first fresh gas flow tube, arranged to provide a
first fresh gas flow; a variable flow continuous positive airway
pressure generator comprising first, second and third connection
portions, wherein the first fresh gas flow tube is connected with
the first connection portion, wherein the generated continuous
positive airway pressure level is adjusted by varying the fresh gas
flow to the variable flow continuous positive airway pressure
generator; a connector connected with the second connection portion
of the variable flow continuous positive airway pressure generator,
wherein the connector is arranged to be connected with an infant
interface; and a pressure release valve, arranged to prevent an
excessive positive pressure in a positive pressure ventilation
mode; wherein the third connection portion embodies an outlet, the
device further comprising: a second fresh gas flow tube, arranged
to provide a second fresh gas flow, which is added to the first
fresh gas flow in the positive pressure ventilation mode.
2. The device according to claim 1, wherein the second fresh gas
flow tube is connected with one of the connector and the third
connection portion.
3. The device according to claim 1, wherein the pressure release
valve is connected with one of the second fresh gas flow tube, the
connector, and the third connection portion.
4. The device according to claim 1, wherein the second fresh gas
flow tube is connected with the connector.
5. The device according to claim 1, wherein the second fresh gas
flow tube is connected with the third connection portion.
6. The device according to claim 5, wherein the second fresh gas
flow tube is connected through a wall of the third connection
portion, wherein the third connection portion comprises an open end
defining the outlet.
7. The device according to claim 1 where the first fresh gas flow
to the variable flow continuous positive airway pressure generator
is 3-12 liters per minute and the second fresh gas flow is 3-12
liters per minute.
8. The device according to claim 1, further comprising a pressure
measuring device.
9. A system for positive pressure ventilation and continuous
positive airway pressure treatment for neonatal resuscitation
comprising a device according to claim 1, and a fresh gas
connection unit, connected with the first and second fresh gas flow
tubes, and connectable to at least one fresh gas source.
10. The system according to claim 9, arranged such that when the
open end outlet of the outlet of the variable flow continuous
positive airway pressure generator is occluded the pressure will
increase from the variable continuous positive airway pressure
generator until the opening pressure of the release valve is
reached, the increase in pressure results to an inspiratory flow,
the pressure in the system will remain at the set positive pressure
ventilation pressure until the outflow occlusion is removed, when
the occluded outflow is opened the pressure will return to the set
continuous positive airway pressure level and this reduction in
pressure will lead to an expiratory flow.
11. The system according to claim 9, arranged such that during
spontaneous breathing, the infant flow and the fresh gas flow
leaves the breathing system over the variable flow continuous
positive airway pressure generator keeping the positive pressure
within the airway stable, by varying the fraction of flow that
generates the continuous positive airway pressure pressure the
continuous positive airway pressure in the airway can be adjusted
as needed.
12. Use of a device according to claim 1 in positive pressure
ventilation and continuous positive airway pressure treatment for
neonatal resuscitation.
13. Use of a system according to claim 9 for positive pressure
ventilation and continuous positive airway pressure treatment for
neonatal resuscitation.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a device and a system for
positive pressure ventilation (PPV) and continuous positive airway
pressure (CPAP) treatment for neonatal resuscitation and initial
respiratory support. The device and system is designed and tested
for preterm and term neonatal use.
BACKGROUND OF THE INVENTION
[0002] Today there are primarily two systems for positive pressure
ventilation in use, i.e. the simple T-piece or a bag. Both use a
mask as an interface to the child but can also be used via an
ET-tube. The two systems are easy to handle, uncomplicated and
inexpensive and have been in use for many decades.
The T-piece systems are able to provide positive pressure
ventilation as well as CPAP for a breathing infant but the bag
systems are unable to provide CPAP for the breathing infant.
[0003] In neonatal resuscitation there is a need for both
ventilation (PPV) of the non-breathing child and support by CPAP
for the spontaneously breathing child. The need for both types of
support is common and changes over time during the resuscitation
period.
[0004] An example of a T-piece system is disclosed in U.S. Pat. No.
4,502,481, where an inspiratory tube provides a fresh gas flow from
a fresh gas source to the patient mask, and an expiratory tube
outlets used gas from the patient mask via a two-way exhaust valve.
In the CPAP mode the T-piece system feeds pressurised fresh gas to
the patient mask and outlets used gas and excessive fresh gas
through a first path of the exhaust valve which is set at a
relatively low opening pressure. In the PPV mode, this path is
manually intermittently occluded. When occluded the pressure at the
patient mask rises and fresh gas is forced into the patient. When
not occluded the patient exhales. If reaching a maximum allowed
pressure before the occlusion is removed, the second path of the
exhaust valve opens to avoid patient injury.
[0005] Thus, the T-piece systems can also provide both PPV and
CPAP. However, these systems expose the neonate to a higher imposed
work of breathing than most of the specialised CPAP systems. This
may lead to extended period of PPV. This could be overcome by
switching between two systems--one for PPV and a specialised system
for CPAP but this is unpractical in the resuscitation period.
Furthermore, specialised CPAP systems are comparatively
expensive.
[0006] Therefore there is a need within the technical field of
PPV/CPAP treatment for neonatal resuscitation to overcome the
problems that exist today. There is a need to achieve an easy
switch between PPV and CPAP for respiratory support without change
of equipment and to provide a low imposed work of breathing for the
breathing child treated with CPAP.
SUMMARY OF THE INVENTION
[0007] It is an object of the present invention to provide a device
for PPV and CPAP treatment that alleviates the above mentioned
problems.
[0008] The object is achieved by a device for PPV and CPAP
treatment according to the present invention as defined in claim
1.
[0009] Thus, in accordance with an aspect of the present invention,
there is provided a device for positive pressure ventilation and
continuous positive airway pressure treatment for neonatal
resuscitation comprising: [0010] a first fresh gas flow tube,
arranged to provide a first fresh gas flow; [0011] a variable flow
continuous positive airway pressure generator comprising first,
second and third connection portions, wherein the first fresh gas
flow tube is connected with the first connection portion, wherein
the generated continuous positive airway pressure level is adjusted
by varying the fresh gas flow to the variable flow continuous
positive airway pressure generator; [0012] a connector connected
with the second connection portion of the variable flow continuous
positive airway pressure generator, wherein the connector is
arranged to be connected with an infant interface; and [0013] a
pressure release valve, arranged to prevent an excessive positive
pressure in a positive pressure ventilation mode;
[0014] wherein the third connection portion embodies an outlet, the
device further comprising: [0015] a second fresh gas flow tube,
arranged to provide a second fresh gas flow, which is added to the
first fresh gas flow in the positive pressure ventilation mode.
[0016] The device is designed and tested for preterm and term
neonatal use. It is not intended for adult use. The device is easy
to use and allows rapid switch between PPV and CPAP without change
of equipment. A safe and quick switch between these types of
respiratory support will improve care for an unstable child and
lead to higher quality in resuscitation with reduced mortality and
morbidity. Due to the second fresh gas tube, the inspiratory flow
in the PPV mode is increased, such that when the outlet is occluded
the second flow adds to the first flow and rapidly increases the
pressure and generates an inspiration. Furthermore, the device
significantly reduces the imposed work of breathing for a breathing
child treated with CPAP, inter alia due to the absence of
mechanical valves at the outlet. A reduction of imposed work of
breathing should lead to higher quality in resuscitation with
reduced mortality and morbidity. It should also reduce the need for
PPV.
[0017] For purposes of this invention, the words "infant" and
"child" are intended to encompass a patient such as a newborn, a
neonatal child which is in need of neonatal resuscitation and
initial respiratory support.
[0018] For purposes of this invention, the wording "fresh gas flow"
is compressed air, compressed oxygen or a mixture of these that
flows through the system and its parts and the wording "fresh gas
flow tube" is wherein the fresh gas flows.
[0019] For purposes of this invention, the wording "bypass gas
flow" will be used as a synonym to "second fresh gas flow", since
the second fresh gas flow does not drive the variable flow CPAP
generator as does the first fresh gas flow, i.e. in a sense the
second fresh gas flow bypasses the variable flow CPAP generator.
The wording "fresh gas flow" is compressed air, compressed oxygen
or a mixture of these that flows through the device or system and
its parts, and the wording "tube" is wherein the fresh gas
flows.
[0020] For purposes of this invention, the wording "variable flow
CPAP generator" is a device intended to encompass any continuous
positive airway pressure device were the CPAP level is adjusted by
varying the fresh gas flow.
[0021] For purposes of this invention, the wording "imposed work of
breathing" is the additional work required to breathe through a
device and is an established way of measuring the pressure
stability of a system. Imposed work of breathing is obtained by
calculating the area within a pressure-volume loop for one
breath.
[0022] For purposes of this invention, the word "infant interface"
is intended to encompass any interface that is suitable for
connecting to an infant or child, such as a pair of nasal prongs, a
mask or any other suitable device.
[0023] In accordance with an embodiment of the device, the second
fresh gas flow tube is connected with one of the connector and the
third connection portion. These are two alternative ways of
arranging the second fresh gas flow tube in order to achieve the
advantages set forth above.
[0024] In accordance with an embodiment of the device, the pressure
release valve is connected with one of the second fresh gas flow
tube, the connector, and the third connection portion. These are
three alternative ways of arranging the pressure release valve,
where the main aim is to arrange it in a position where the
pressure of interest is measurable in a reliable way.
[0025] In accordance with an embodiment of the device, the second
fresh gas flow tube is connected through a wall of the third
connection portion, wherein the third connection portion comprises
an open end defining the outlet. This embodiment emphasizes the
absence of mechanical valves, such as the overpressure valve 13 of
the prior art device disclosed in U.S. Pat. No. 4,502,481, as
described above, thereby minimising the imposed breathing work.
[0026] In accordance with an embodiment of the device, the first
fresh gas flow in the device to the variable flow CPAP generator is
in the range of 3-12 liters per minute and the second fresh gas
flow is in the range of 3-12 liters per minute.
[0027] In accordance with an embodiment of the device, it further
comprises a pressure measuring device. Thereby, it is possible to
easily monitor the operation of the device and make desirable
adjustments of for instance the first fresh gas flow. Preferably,
the pressure measuring device is connected with the connector or
with the second fresh gas flow tube in case the second fresh gas
flow tube, in turn, is connected with the connector.
[0028] The different embodiments of the device can be summarized as
a device comprising a first fresh gas flow tube connected to a
variable flow CPAP generator, a connector connected to the variable
flow CPAP generator, a bypass flow tube connected to an outlet of
the variable flow CPAP generator or to the connector, a pressure
release valve connected to the outlet of the variable flow CPAP
generator or to the connector or to the bypass flow tube, and a
pressure measuring device connected to the connector or to the
bypass flow tube if the bypass flow tube is connected to the
connector.
[0029] According to another aspect of the present invention, there
is provided a system for positive pressure ventilation and
continuous positive airway pressure treatment for neonatal
resuscitation comprising a device as described above, and a fresh
gas connection unit, connected with the first and second fresh gas
flow tubes, and connectable to at least one fresh gas source. Thus,
the system includes the connection unit which is connected to at
least one fresh gas source. In case of a single fresh gas source,
the connection unit is a device which splits the received fresh gas
flow in two flows, which are conducted into the first fresh gas
flow tube and into the second fresh gas flow tube, respectively.
Multiple fresh gas sources may be used to provide either the same
fresh gas in two different paths, or different fresh gases, which
are mixed in the fresh gas connection unit.
[0030] In accordance with an embodiment of the system, it is
arranged such that when the open end outlet (8) of the outlet (4)
of the variable flow CPAP generator is occluded the pressure will
increase from the variable CPAP generator until the opening
pressure of the release valve (6) is reached, the increase in
pressure results to an inspiratory flow, the pressure in the system
will remain at the set positive pressure ventilation pressure until
the outflow occlusion is removed, when the occluded outflow is
opened the pressure will return to the set CPAP level and this
reduction in pressure will lead to an expiratory flow.
[0031] In accordance with an embodiment of the system, it is
arranged such that during spontaneous breathing, the infant flow
and the fresh gas flow leaves the breathing system over the
variable flow CPAP generator 3 keeping the positive pressure within
the airway stable, by varying the fraction of flow that generates
the CPAP pressure the CPAP pressure in the airway can be adjusted
as needed.
[0032] The device as disclosed above can be used in positive
pressure ventilation and continuous positive airway pressure
treatment for neonatal resuscitation.
[0033] The system as disclosed above can be used for positive
pressure ventilation and continuous positive airway pressure
treatment for neonatal resuscitation.
[0034] These and other aspects, and advantages of the invention
will be apparent from and elucidated with reference to the
embodiments described hereinafter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] The invention will now be described in more detail and with
reference to the appended drawings. The drawings are included to
provide a further understanding of the present invention and are
incorporated in and are a part of this specification. Other
embodiments of the present invention, and many of the intended
advantages of the present invention, will be readily appreciated as
they become better understood by reference to the following
detailed description. The elements of the drawings are not
necessarily to scale relative to each other. The same reference
numerals designate corresponding similar parts.
[0036] FIG. 1 is a schematic illustration of an embodiment of the
device according to the present invention;
[0037] FIGS. 2-4 are schematic illustrations of further embodiments
of the device;
[0038] FIGS. 5a-5c schematically illustrate flows in an embodiment
of the system according to the present invention, during positive
pressure ventilation;
[0039] FIG. 6 schematically illustrates flows in the system shown
in FIGS. 5a-5c during spontaneous ventilation;
[0040] FIG. 7 is a scatter plot showing the imposed work of
breathing at different levels of CPAP, the mean pressure, for
different systems determined by simulated breathing in a mechanical
lung model; and
[0041] FIG. 8 schematically illustrates another embodiment of the
system.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0042] For resuscitation and stabilisation of newborn infants two
types of mechanical respiratory support are common depending on
whether the infant is breathing or not. Positive pressure
ventilation is used for the non-breathing infant and continuous
positive airway pressure for the breathing infant. An infant that
is not breathing after birth should be ventilated. This can be
accomplished with PPV using e.g. a face mask, or an endotracheal
tube. In the majority of cases a mask is used. If the infant starts
to breath or was breathing after birth, support of ventilation
using CPAP is the recommended treatment for several conditions.
After return of spontaneous breathing some infants will still need
PPV intermittently as they stop breathing. This is especially
common when treating premature neonates.
[0043] The advantages with the present invention is that it allows
rapid and easy switch, without change of equipment, between PPV and
CPAP treatment in combination with a significant reduction in
imposed work of breathing compared to available devices. Today in
order to provide CPAP with low imposed work of breathing a device
that is unable to provide PPV has to be used. Should the infant
require ventilation a switch to another system able to provide
positive pressure ventilation will be needed such as a bag or
T-piece system.
[0044] There are examples of different embodiments of the present
invention. Common for the embodiments described herein is that they
comprise a first fresh gas flow tube 1, a second fresh gas flow
tube 2, a variable CPAP generator 3, a connector 9, and a pressure
release valve 6. Some embodiments additionally comprise a pressure
measuring device 7. Furthermore, the variable flow CPAP generator 3
comprises a first connection portion, a second connection portion,
and a third connection portion 4. In all embodiments, the first
fresh gas flow tube 1 is connected with the first connection
portion of the variable flow CPAP generator 3; the connector 9 is
connected with the second connection portion; and the third
connection portion 4 embodies an outlet 4 of the variable flow CPAP
generator 3. The outlet 4 typically is tubular, and is arranged as
a protruding tube ending at a free open end. There are no
mechanical valves as in the prior art described above. The
connector 9 is typically realised as a tube having a first end
connected with the second connection portion, and a second end is
connectable with any infant interface 5, examples of which have
been given above.
[0045] The second fresh gas flow tube will also be called bypass
flow tube, since in most embodiments and operation modes the second
fresh gas flow will bypass the variable CPAP generator 3. The
bypass flow tube 2, the pressure measuring device 7 and the
pressure release valve 6 can be arranged in several different
positions, see FIGS. 1-4. The pressure measuring device 7 can be
omitted in any embodiment if there is no interest in measuring the
pressure.
[0046] As disclosed in FIG. 1, according to a first embodiment of
the device 100, the bypass flow tube 2 is connected to the
connector 9, i.e. through the wall of the connector 9, between the
variable flow CPAP generator 3 and infant interface 5. This
connection of the bypass flow tube 2 is preferred. The pressure
release valve 6 and the pressure measuring device 7 are connected
to the bypass flow tube 2.
[0047] As disclosed in FIG. 2, according to a second embodiment of
the device 200, the bypass flow tube 2 is connected to the outlet
4, i.e. through the wall of the outlet 4, of the variable flow CPAP
generator 3. The pressure release valve 6 and the pressure
measuring device 7 are connected to the connector 9 between the
infant interface 5 and the variable flow CPAP generator 3.
[0048] As disclosed in FIG. 3, according to a third embodiment of
the device 300, the bypass flow tube 2 is connected to the outlet 4
of the variable flow CPAP generator 3. The pressure release valve 6
is connected on the bypass flow tube 2. The pressure measuring
device 7 is connected to the connector 9 between the infant
interface 5 and the variable flow CPAP generator 3.
[0049] As disclosed in FIG. 4, according to a fourth embodiment of
the device 400, the bypass flow tube 2 is connected to the
connector 9 between the variable flow CPAP generator 3 and the
infant interface 5. The pressure release valve 6 and the pressure
measuring device 7 are connected to the connector 9 between the
infant interface 5 and the variable flow CPAP generator 3.
[0050] A first embodiment of the system 500, as disclosed in FIGS.
5a-5c and 6, comprises the first embodiment of the device 100. The
system further comprises a fresh gas connection unit 11, which is
connected to a fresh gas flow 10 originating from a fresh gas
source (not shown). The fresh gas connection unit 11 is a shunt,
which splits the fresh gas flow 10 into the first and second fresh
gas flows fed through the first and second fresh gas flow tubes 1,
2, respectively, and adjusts the level of CPAP.
[0051] A second embodiment of the system 800, as disclosed in FIG.
8, comprises the second embodiment of the device 200, and a fresh
gas connection unit 11.
[0052] The system is operated as follows. Reference will be made to
the first embodiment of the system 500, but the second embodiment
800 has a corresponding operation. Oxygen concentration and fresh
gas flow are adjusted by a standard blender and a flow meter. The
fresh gas flow could be varied and typically between 10-15 liters
(l) per minute. A fresh gas flow in this range should prevent
rebreathing, provide flow to achieve an adequate inspiration flow,
volume and time, and provide some allowance for leak in the infant
interface 5.
[0053] The fresh gas flow 10 can be supplied from two different gas
sources or from the same gas source. If one gas source is used then
the fresh gas flow is divided into two fractions. The fresh gas
flow can be divided using a shunt valve or double rotameter or any
other device capable of dividing a gas flow. One part of the fresh
gas flow, i.e. the first fresh gas flow, is used to drive the
variable flow CPAP generator 3 and the other part of the fresh gas
flow, i.e. the second fresh gas flow or bypass flow, is used to
supply adequate flow for positive pressure ventilation by bypassing
the variable flow CPAP generator 3. The bypass flow is connected in
such a way that it adds to inspiratory patient flow when the device
is occluded during positive pressure ventilation. The first fresh
gas flow to the variable CPAP generator 3 is always adjustable. The
bypass flow can be varied or fixed. A typical value of the first
fresh gas flow to the variable flow CPAP generator is 3-12 liters
per minute and the bypass flow is 3-12 liters per minute. The sum
of the first fresh gas flow and the bypass flow will typically be
between 10-15 l per minute. To provide high CPAP the flow driving
the variable flow CPAP generator can be increased further until the
bypass flow is zero. This would generate a CPAP that is higher than
normally used.
[0054] The outlet 4 of the variable flow CPAP generator 3 has an
open end outlet 8. If the open end outlet 8 is occluded, see FIGS.
5a and 5b, the pressure delivered to the infant will increase from
the pressure set by the variable CPAP generator 3 until the opening
pressure of the release valve 6 is reached. A typical value for the
pressure release valve 6 to open is around 20-30 cm H.sub.2O. The
increase in pressure results in an inspiratory flow. The pressure
in the system 500 will remain at the set positive pressure
ventilation pressure until the outlet occlusion is removed. When
the occluded open end outlet 8 is opened, see FIG. 5c, the pressure
delivered to the patient will return to the set CPAP level and this
reduction in pressure will lead to an expiratory flow.
[0055] During spontaneous breathing the infant flow and the fresh
gas flow leaves the breathing system over the variable flow CPAP
generator 3, see FIG. 6. This keeps the positive pressure within
the airway stable. By varying the fraction of flow, i.e. the first
fresh gas flow, that generates the CPAP pressure, the CPAP pressure
in the airway can be adjusted as needed. The first fresh gas flow
drives the variable flow CPAP generator 3 and the bypass flow
bypasses the variable flow CPAP generator 3.
[0056] The connector 9 between variable flow CPAP generator 3 and
infant interface 5 can be designed in any suitable form.
[0057] The system could have a backup system for malfunctioning of
the pressure release valve 6. This could either be an alarm, a
second release valve or a system that cuts the fresh gas flow.
[0058] The infant interface 5 can assume a variety of designs
suitable for establishing a connection to the infant nasal airways,
not shown. Thus, the infant interface 5 can include an opposing
pair of nasal prongs, a mask or any other suitable devices.
[0059] The pressure measuring device 7 should be positioned as
close to the infant as possible to provide accurate recording of
the pressure of the gas delivered to the infant. The accuracy will
depend on the flow resistance of the infant interface 5 and a low
resistance interface should be used if possible. The first
embodiment of the device 100 could be regarded as beneficial since
there will be less tubes needed in the system.
[0060] A comparison of the reduction in imposed work of breathing
at different levels of CPAP is made between two embodiments of the
present invention and two other systems, and the results are
disclosed in FIG. 7. The mean pressure is the average pressure for
one breath and is very similar to CPAP. Imposed work of breathing
is the additional work required to breathe through a device and is
an established way of measuring the pressure stability of a system.
Imposed work of breathing is obtained by calculating the area
within a pressure-volume loop for one breath. In FIG. 7 the GE
Healthcare T-piece is represented by diamonds, Neopuff.TM. from
Fisher & Paykel is represented by squares, prototype A is
represented by crosses and prototype B is represented by circles.
Prototype A uses the device described in FIG. 1 and prototype B
uses the device described in FIG. 3.
[0061] Notably, the device, in accordance with principles of the
present invention is useful with a wide variety of infant interface
configurations that may or may not incorporate some or all of the
features described above with respect to the infant interface.
Thus, the infant interface is in no way limiting. The infant
interface is connected to the open end of the connector 9, i.e. the
end which is not connected to the variable flow CPAP generator
3.
[0062] Notably, the device, in accordance with principles of the
present invention is useful with a wide variety of variable flow
CPAP generators that may or may not incorporate some or all of the
features described above with respect to the variable flow CPAP
generators. Thus, the model of the variable flow CPAP generator is
in no way limiting.
[0063] Notably, the device, in accordance with principles of the
present invention is useful with a wide variety of pressure release
valves or similar devices that achieves the purpose releasing air
depending on the pressure in the system. Thus, the model or type
pressure release valve is in no way limiting.
[0064] Notably, the device, in accordance with principles of the
present invention is useful with a wide variety of pressure
measuring devices or similar devices that achieves the purpose of
measuring the pressure in the system. Thus, the model or type
pressure measuring devices is in no way limiting.
EXAMPLES
[0065] In the examples disclosed below the performance of the
invention in simulated neonatal breathing is illustrated.
[0066] The additional work needed to breathe through a device can
be established by determining imposed work of breathing. This is
the additional energy needed for one breath and is closely related
to maintaining a stable airway pressure. The imposed work of
breathing can be determined in simulated breathing in a mechanical
lung model by calculating the area within the pressure-volume loop
for one breath.
[0067] The method used in the tests is the mechanical lung model
which uses a symmetrical sinusoid flow pattern with a flow maximum
of 6 litres per minute and a respiratory rate of 60 breaths per
minute. The systems and prototypes were all tested at room
temperature with piped medical air and a fresh gas flow of 12
litres per minute. Two commercially available T-piece devices were
tested, the GE Healthcare T-piece and the Neopuff.TM. from Fisher
& Paykel, and two prototypes A and B representing the present
invention. Prototype A used the device described in FIG. 1 and
prototype B used the device described in FIG. 3. The parts used for
the two prototypes were 1) low resistance connectors between infant
interface 5 and positive pressure release valve 6 with the
narrowest diameter of >6 mm in prototype A, and 6 mm in
prototype B; 2) low resistance connectors between infant interface
5 and open end outlet 8 with a narrowest part of 2.times.3.5 mm
diameter; 3) low restive infant interface 5 with a narrower part of
3.times.3.5 mm diameter; 4) the pressure release valve 6 used was a
Berner valve; 5) the pressure measure device 7 was a standard
mechanical pressure meter; 6) double rotameters were used as a
shunt 11 to divide the fresh gas flow 10 and adjust the level of
CPAP (mean pressure); 7) The variable flow CPAP device 3 was a jet
device. 8) Other connectors or tubes had varying flow resistance
and diameters.
[0068] The results of the imposed work of breathing at different
mean pressures for the tested systems are presented in FIG. 7. One
mark represents the energy needed for one breath at that mean
pressure.
[0069] The results in FIG. 7 clearly show the significant reduction
in imposed work of breathing for a device according to the present
invention illustrated by the two prototypes A and B compared to the
tested T-piece devices.
[0070] A typical CPAP level for resuscitating or stabilising an
infant is in the range of 5-10 cm H.sub.2O. A typical peak pressure
for PPV is 20-30 cm H.sub.2O. It is obtained by occluding the
systems, prototypes or T-piece device, respectively and having a
correctly adjusted pressure release valve.
[0071] Above embodiments of the device and system according to the
present invention as defined in the appended claims have been
described. These should only be seen as merely non-limiting
examples. As understood by the person skilled in the art, many
modifications and alternative embodiments are possible within the
scope of the invention as defined by the appended claims.
[0072] It is to be noted that for the purposes of his application,
and in particular with regard to the appended claims, the word
"comprising" does not exclude other elements or steps, and the word
"a" or "an" does not exclude a plurality, which per se will be
evident to a person skilled in the art.
* * * * *